It turns out that running an event handler (onProvideCompletionsFromXXXX) in the same component/page may result in various race condition problems.
Suppose you have a complex form and data initialization occurs during onActivate phase. Then, this initialization is going to happen every time onProvideCompletions handler is called. If this initialization involves for example Hibernate objects loading, in several situations I get 'session is closed' errors (in fact this is very unpredictable - the same operation under same conditions may either work normally or fail). Are there any suggested methods to make autocomplete data source totally independent from current component? -- Ilya Obshadko